Time-of-flight ranging sensor and time-of-flight ranging method

Abstract

A time-of-flight ranging sensor and a time-of-flight ranging method are provided. The time-of-flight ranging sensor includes a signal processing circuit, a light emitter, and a light sensor. The light emitter emits a pulsed light having a first polarization direction to a sensing target. The light sensor senses the pulsed light reflected by the sensing target to output a first sensing signal via a first sub-pixel repeating unit and output a second sensing signal via a second sub-pixel repeating unit to the signal processing circuit. The signal processing circuit determines a pulse signal according to the first sensing signal and the second sensing signal, and the signal processing circuit determines a depth information of the sensing target according to the pulsed light and the pulse signal.

What is claimed is: 
     
         1 . A time-of-flight ranging sensor, comprising:
 a signal processing circuit;   a light emitter coupled to the signal processing circuit and configured to emit a pulsed light having a first polarization direction to a sensing target; and   a light sensor coupled to the signal processing circuit and configured to sense the pulsed light reflected by the sensing target to output a first sensing signal via a first sub-pixel repeating unit and a second sensing signal via a second sub-pixel repeating unit to the signal processing circuit,   wherein the first sub-pixel repeating unit comprises a plurality of color sub-pixel units and a first pulsed light sensing unit having the first polarization direction, and the second sub-pixel repeating unit comprises a plurality of other color sub-pixel units and a second pulsed light sensing unit having a second polarization direction,   wherein the signal processing circuit determines a pulse signal according to the first sensing signal and the second sensing signal, and the signal processing circuit determines a depth information of the sensing target according to the pulsed light and the pulse signal.   
     
     
         2 . The time-of-flight ranging sensor of  claim 1 , wherein during a ranging, the light sensor obtains the first sensing signal and the second sensing signal via the first pulsed light sensing unit of the first sub-pixel repeating unit and the second pulsed light sensing unit of the second sub-pixel repeating unit. 
     
     
         3 . The time-of-flight ranging sensor of  claim 1 , wherein the signal processing circuit performs a direct time-of-flight ranging operation to calculate the depth information of the sensing target according to a time difference between when the light emitter emits the pulsed light and when the light sensor senses the pulse signal. 
     
     
         4 . The time-of-flight ranging sensor of  claim 1 , wherein the signal processing circuit performs an indirect time-of-flight ranging operation to calculate a round-trip time of the pulsed light and calculate the depth information of the sensing target according to the round-trip time. 
     
     
         5 . The time-of-flight ranging sensor of  claim 1 , wherein the first sensing signal comprises the pulse signal and a first background noise signal, and the second sensing signal comprises a second background noise signal, wherein signal strengths of the first background noise signal and the second background noise signal are the same, and polarization directions of the first background noise signal and the second background noise signal are different. 
     
     
         6 . The time-of-flight ranging sensor of  claim 5 , wherein the signal processing circuit performs a signal strength subtraction operation on the first sensing signal and the second sensing signal to obtain the pulse signal. 
     
     
         7 . The time-of-flight ranging sensor of  claim 1 , wherein the color pixel units and the other color pixel units respectively comprise a red sub-pixel unit, a green sub-pixel unit, and a blue sub-pixel unit. 
     
     
         8 . The time-of-flight ranging sensor of  claim 1 , wherein the first pulsed light sensing unit and the second pulsed light sensing unit are respectively an infrared sub-pixel unit. 
     
     
         9 . The time-of-flight ranging sensor of  claim 1 , wherein the second polarization direction is perpendicular to the first polarization direction. 
     
     
         10 . A time-of-flight ranging method, comprising:
 transmitting a pulsed light having a first polarization direction to a sensing target via a light emitter;   sensing the pulsed light reflected by the sensing target via a light sensor to output a first sensing signal via a first sub-pixel repeating unit and output a second sensing signal via a second sub-pixel repeating unit; and   determining a pulse signal according to the first sensing signal and the second sensing signal via a signal processing circuit and determining a depth information of the sensing target according to the pulsed light and the pulse signal,   wherein the first sub-pixel repeating unit comprises a plurality of color sub-pixel units and a first pulsed light sensing unit having the first polarization direction, and the second sub-pixel repeating unit comprises a plurality of other color sub-pixel units and a second pulsed light sensing unit having a second polarization direction.